Crane collision prevention control system

Abstract

To provide a collision prevention control system for a crane being an automatic crane simultaneously performing hoisting / lowering operation and horizontal movement so as to enable efficient operation, the collision prevention control system capable of preventing collision between a suspended load and a floor obstacle even when the crane is stopped while the hoisting / lowering operation and the horizontal movement are performed.SOLUTION: In a collision prevention control system for a crane, when an automatic crane CR is hoisted obliquely through a shortest path FR in hoisting operation and horizontal movement in simultaneous execution of the hoisting operation and the horizontal movement on the automatic crane CR, an actual moving path is set rearward in a horizontal movement advancing direction from the shortest path FR only by a braking distance BD relative to a speed at which the horizontal movement occurs.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] To provide a crane collision prevention control system that can prevent a load from colliding with an obstacle even when the automatic crane goes into an abnormal state and deviates from the transport route while the automatic crane is automatically transporting the load along the shortest route while avoiding obstacles. [Background technology]

[0002] When an automatic crane is operated automatically, in the past, to prevent the load from colliding with obstacles such as products placed below the crane, the load was hoisted to a safe height within the crane's operating range to prevent collision with the product, etc., and then the load was moved horizontally, ensuring safe and reliable automatic operation. However, this method of operation requires longer transport times than a manually operated crane that simultaneously performs hoisting and horizontal movement, which means that automatic cranes cannot be used effectively.

[0003] To address this issue, a technology has been introduced in which automatic cranes simultaneously perform hoisting and horizontal movement to transport the object along the shortest route (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-99368 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in a typical overhead crane, the braking distance for horizontal movement is longer than the braking distance for hoisting. Therefore, when a load is being transported by simultaneous hoisting and horizontal movement along the shortest route trajectory that avoids obstacles, if an emergency stop occurs due to a power outage or power interruption, or if an abnormal stop occurs that decelerates and stops all movements in the shortest time, the load will deviate horizontally from the shortest route trajectory, causing a problem of a collision between the load and the obstacle.

[0006] Furthermore, when an overhead crane is performing both traverse and travelling movements simultaneously, if an emergency stop is made due to a power outage or power interruption, or if an abnormal stop is made to slow down and stop all movements in the shortest possible time, the crane may deviate from its route in the direction of its high speed at the time, resulting in a collision between the load and an obstacle.

[0007] In view of the problems inherent in the above-mentioned automatic cranes, the object of the present invention is to provide a collision prevention control system for a crane that can prevent a suspended load from colliding with an obstacle on the floor even if the crane stops during hoisting, lowering, or horizontal movement, in an automatic crane that allows for efficient operation by simultaneously hoisting up and down and horizontal movement. [Means for solving the problem]

[0008] In order to achieve the above object, the crane collision prevention control system of the present invention is characterized in that, in an automatic crane transportation system that simultaneously performs hoisting and horizontal movement, when hoisting obliquely along the shortest path during hoisting and horizontal movement, the actual movement path is set backward in the direction of horizontal movement from the shortest path by an amount corresponding to the braking distance corresponding to the speed at which the horizontal movement occurs. This makes it possible to prevent collisions between the load and obstacles even in the event of an emergency stop due to a power outage or power interruption, or an abnormal stop in which all operations are decelerated and stopped in the shortest possible time.

[0009] In this case, when the transport area of ​​the automatic crane is viewed in a plane, the height at which the highest floor obstacle within the rectangular planar range with the current position and the destination position as diagonal corners can be overcome can be set as the safe height at which horizontal movement can be performed freely. This makes it possible to prevent collisions between the load and obstacles even in the event of an emergency stop due to a power outage or power interruption, or an abnormal stop in which all operations are decelerated and stopped in the shortest possible time.

[0010] Furthermore, when the automatic crane is being hoisted and a space is secured that allows horizontal movement in the direction of the destination, a travelable line is set that is drawn forward from the collision travel line that exists in the travel direction toward the destination position by the braking distance for the travel speed at that time, and a lateral movement possible line is set that is drawn forward from the collision lateral movement line that exists in the lateral movement direction toward the destination position by the braking distance for the lateral movement speed at that time, and the planar range enclosed by a rectangle with the intersection of the travelable line and the lateral movement possible line and the current position as diagonal corners can be made to allow lateral movement or travel operation during hoisting.

[0011] Furthermore, when the height of an obstacle on the floor in a rectangular planar range with the current position and the target position as diagonals begins to decrease with horizontal movement, a simultaneous lowering operation can be performed during horizontal movement, and the height at that time can be set to a position higher by the braking distance for lowering than the height of the clearance dimension for avoiding a collision. [Effects of the Invention]

[0012] According to the crane collision prevention control system of the present invention, even if an unforeseen event such as a power outage or emergency stop occurs when hoisting and horizontal movement, or traversing and traveling, are being performed simultaneously, it is possible to prevent a collision between a suspended load and an obstacle. This makes it possible to ensure safety while safely operating two or more automatic cranes simultaneously, shortening the transport time of the automatic cranes and enabling effective use of the automatic cranes. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an explanatory diagram from the aspect of collision prevention when hoisting and horizontal movement are simultaneously performed in the crane collision prevention control system of the present invention. FIG. [Figure 2] 1 is an explanatory diagram of collision prevention during simultaneous traverse and travel operations in the crane collision prevention control system of the present invention. FIG. [Figure 3] FIG. 1 is a plan view illustrating simultaneous operation of hoisting and horizontal movement in the crane collision prevention control system of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a crane collision prevention control system according to the present invention will be described with reference to the drawings.

[0015] The crane collision prevention control system of the present invention will be described with reference to FIG. 1, taking an automatic crane CR for transporting steel coils as an example.

[0016] Conventionally, with the automatic cranes CR used to transport steel coils, the coils CO lined up on the floor FL of the coil storage area were subject to a limit on the height to which they could not be stacked as a work standard, and the automatic crane CR was only used to lift the coils vertically, without any horizontal movement. At this time, the height at which the underside of the suspended load HW exceeds the restricted height was set as the safe height, and horizontal movement was carried out at a height exceeding this safe height. However, although this operation method is safe and reliable, the transport time of the automatic crane CR is However, there is a problem that the transport time of an automatic crane CR is longer than that of a manual crane operated by a crane operator, and there has been a demand for technology that shortens the transport time of an automatic crane CR to the same level as a manual crane by performing simultaneous hoisting and horizontal movements at an angle, as disclosed in Patent Document 1.

[0017] The automatic crane CR performs simultaneous lifting and horizontal movement operations, and the height at which it clears the coil CO on the floor FL is calculated by adding the outer radius and hole radius of the load coil downward to the height of the top surface of the gripping claws of the lifting device to calculate the height of the bottom surface of the load coil.By setting a predetermined gap dimension (usually around 500 mm) between the height of the top surface of the coil CO placed on the floor FL and the bottom surface of the load and operating the automatic crane CR along the shortest route FR, it is possible to realize an automatic crane CR with a shorter operating time than a manual crane.

[0018] Incidentally, a typical automatic crane CR for transporting steel coils is set to have a hoisting speed HV of about 0.2 m per second, a traveling speed LV of about 2 m per second, and a traverse speed of about 1 m per second. This speed varies depending on the application of the automatic crane CR, but the tendency is similar in that the hoisting speed HV is slow and horizontal movements such as traveling and traversing are fast. In the example of this automatic crane CR, the ratio of the hoisting speed HV to the traveling speed LV is 10 times faster, but because the braking distance is proportional to the square of the speed, a simple calculation shows that the braking distance for traveling is 100 times longer than the braking distance for hoisting. Furthermore, while the moving weight for hoisting is only the load, for traveling the moving weight is the weight of the load plus the weight of the crane, which moves at high speed, resulting in a large inertial force for traveling. Furthermore, for hoisting, the load is pulled downward by gravity, so this downward pull on the load acts as a braking force during hoisting, making the braking distance in the hoisting direction even shorter. In this embodiment, when normal deceleration is performed using the braking force of the speed control device, the braking distance for hoisting is approximately 0.1 m, the braking distance for traveling is approximately 15 m, and the braking distance for traversing is approximately 3.8 m.

[0019] When a gap is created between the coil CO placed on the floor and the load is operating diagonally upwards on the shortest route FR with a 1:10 ratio between the hoisting speed HV and the traveling speed LV, if the normal deceleration and stop of the hoisting and traveling is performed, the hoisting will immediately stop at about 0.1 m, the traveling will move a large distance of about 15 m, and in a situation where the load HW cannot be raised completely, it will move in the traveling direction on the emergency route ER while maintaining a nearly horizontal height, causing the coil of the load HW to collide with the coil CO placed on the floor.

[0020] Furthermore, if an emergency stop or power outage occurs due to a power cut while the lifting and horizontal movements are being performed simultaneously and the lifting and horizontal movements are moving diagonally upward along the shortest route FR, the lifting and horizontal movements will move almost horizontally along the emergency route ER, just as they would during the normal deceleration stop described above, and a collision will occur.

[0021] The brakes of the automatic crane CR are of the so-called inoperative type, which are released by passing a current through the brake and applied by cutting off the current. Therefore, the vehicle can be stopped safely by braking in the event of an emergency power outage or a power outage, but since horizontal movement such as traveling has a large inertia force, the braking distance for horizontal movement such as traveling becomes long, just as in the case of a normal deceleration stop using a speed control device. At this time, it is necessary to select an appropriate brake torque so that the braking distance when stopping due to an emergency power outage or a power outage is not longer than that required for normal deceleration and stopping. Incidentally, even if the braking torque is excessive in an attempt to drastically shorten the braking distance for traversing or traveling, the wheels will lock when the brakes are applied, causing the wheels to slip on the rails. The braking distance when a slip occurs is longer than the braking distance required for normal deceleration and stopping, so there is a limit to how much the braking distance can be shortened, even if the braking torque is made too strong. Furthermore, if the machine stops due to an emergency power outage or power outage, the anti-sway control will not work. Therefore, the braking distance BD needs to be set to a larger value taking into account the amount of load sway.

[0022] Therefore, in order to avoid obstacles such as coils CO placed on floor FL and transport the load HW in the shortest time possible, the crane collision prevention control system of the present invention first derives the shortest route FR that will move the load HW by reducing the gap between the obstacle such as coils CO on floor FL and the load HW to a predetermined limit dimension, then draws a safety route SR line behind the shortest route FR in the direction of travel of the automatic crane's horizontal movement, a braking distance BD for the horizontal movement, and controls the load HW to move along that line. This prevents the load from colliding with the coil CO on the floor FL even if there is a power outage, emergency stop, or normal stop while the lifting and horizontal movements are simultaneously in operation.

[0023] Incidentally, when stopping simultaneous hoisting and horizontal movements, the braking distance for the horizontal movement is extremely large compared to the braking distance for the hoisting, so when stopping simultaneous hoisting and horizontal movements, the movement path of the load HW deviates significantly in the direction of colliding with an obstacle on floor FL. When stopping simultaneous lowering and horizontal movements, the braking distance for lowering is extremely small compared to the braking distance for the horizontal movement, so the path deviates in the direction of avoiding the collision, and the obstacle on floor FL and the load move away from it, so when simultaneous lowering and horizontal movements are performed, it is only necessary to move the load upward a short distance, just the braking distance for lowering.

[0024] If an emergency stop occurs due to a power outage or power interruption while the crane is traveling or traversing, the inertial force of the traveling or traversing motion is used to stop the crane by the rolling resistance of the wheels and the frictional force of the brakes, but the resistance of the wheels changes depending on the contact of the wheel ribs and the condition of the rails, and the frictional resistance of the brakes also changes depending on the humidity, temperature and the condition of the friction material, so the braking distance changes depending on the situation at the time.The braking distance also changes if the load is swinging. At rated speed, the traveling speed is 2 to 3 times the traversing speed, so the braking distance is 4 to 9 times greater. If an emergency stop occurs due to a power outage or power interruption while the traversing and traveling are operating simultaneously, the current should flow to the traveling side, but the way this flows varies depending on the speed at the time and the conditions of the brakes, etc.

[0025] Taking these uncertainties into consideration, the range within which safety is desirable when performing simultaneous traverse and travel operations is the range enclosed by a rectangle RA with diagonals connecting the current position CL and the destination position DL, as shown in the plan view of Figure 2. By moving the load HW at a height that allows it to overcome the maximum height of any obstacle on the floor FL within this range, collisions between the load HW and obstacles on the floor FL can be prevented, and simultaneous traverse and travel operations can be performed safely. In this case, if the traverse coordinates or travel coordinates of the current position CL and the destination position DL are the same and only one of traverse or travel is performed, the rectangle RA will be a long, thin, straight rectangle RA with its short side being the movement width of the coil.

[0026] Next, a method for preventing collisions during the process of moving a gripped coil from a current position CL to a target position DL using a control method that operates in a sequential control manner will be described based on an embodiment.

[0027] In the first step, the coil gripping point is set as the current position CL, the storage location to which the coil is moved is set as the destination position DL, and a height that can overcome the height of the highest coil CO in the area enclosed by a rectangle RA with the current position CL and the destination position DL as diagonals is set as a safety height SH, and the winding operation is performed at high speed up to the safety height SH. At this time, if there are no coils CO other than the coil CO to be transported placed within the area enclosed by the rectangle RA, the safety height SH will be set to a height that avoids the coil CO storage stand, and traverse and travel will be performed. Also, if there is even one coil CO stacked three high within the area enclosed by the rectangle RA where two-high coils CO are lined up, the safety height SH will be set to a height that avoids the three-high coil CO. The safety height SH is set as the target value, and the lifting is performed.

[0028] In the second step, while the coil CO to be transported in the first step is being gripped and wound up, when a certain distance is secured between the coil CO and the obstacle on the horizontal plane in the direction of the destination position DL at a height midway through the winding, horizontal movement during winding is initiated. Specifically, as shown in FIG. 3, a travelable line LS is drawn a distance BD shorter than the traveling collision distance LP, which is the distance between the current position CL and a traveling collision line LC where an obstacle exists on the traveling TL side in the direction of the destination position DL, and a lateral movement possible line SS is drawn a distance BD shorter than the lateral movement distance SP, which is the distance between the current position CL and a lateral movement collision line SC where an obstacle exists on the lateral movement TS side. The coordinate point of the horizontally movable diagonal position DP, which is the intersection of this travelable line LS and the lateral movement possible line SS, is placed on a plane, and the lateral movement TS and traveling TL can be started while being hoisted within the range enclosed by a rectangle RA2 whose diagonals are the current position CL and the horizontally movable diagonal position DP, and three-motion operation can be performed. The travel speed command value and lateral speed command value set at this time are determined in proportion to the distances of the travel collision distance LP and the lateral collision distance SP, but if these speed target values ​​are set large, the value of the lateral or travel braking distance BD will increase in proportion to the square of the respective speeds, shortening the distance from the current position CL to the horizontally movable diagonal position DP and reducing the range enclosed by the rectangle RA2, resulting in inefficient operation with repeated acceleration and deceleration. To prevent this, the lateral speed and travel speed at this time are set moderately, allowing for smooth and efficient operation. At this time, the camera moves in the winding, traveling and traversing directions and the speed also changes, so the coordinate points of the current position CL and the horizontally movable diagonal position DP change successively. Incidentally, when the distance to the obstacle is secured in only one direction, that is, traversing or traveling, the rectangle RA2 having the current position CL and the horizontally movable diagonal position DP as its diagonal corners becomes a long, thin rectangle of the moving width of the linear coil, and in this case, two operations, the movement in the direction of the long side of the rectangle RA2 for traversing or traveling and the winding-up, are performed simultaneously. Then, when the hoisting position reaches the safety height SH, hoisting is stopped. Then, since there are no collision obstacles in the horizontal direction up to the destination position DL, horizontal movement can be performed at full speed toward the destination position DL without any restrictions on traverse speed or running speed.

[0029] In the third step, as the robot moves laterally and travels toward the destination position DL, and the current position CL approaches the destination position DL horizontally, when the robot passes the position of the highest coil CO that was initially set at the safety height SH, the height of the highest coil CO within the range enclosed by the rectangle RA with the current position CL and the destination position DL as diagonals decreases, and the safety height SH decreases. Accordingly, lowering is started during traverse and traveling, and the lowering operation is performed during traverse and traveling up to the safety height SH. Then, every time the safety height SH is updated, the lowering operation is started during traverse and traveling, and the machine heads toward the target position DL. At this time, even if there is no coil CO around the destination position DL, the height at which the coil avoids the stand is the safety height SH, so when the positioning of the traverse and travel is completed at the destination position DL, the height restriction, including the height of the stand, is lifted, and the coil can be placed on the destination stand.

[0030] In the third step, when the lowering, lateral movement, and traveling movement are performed simultaneously, there are no obstacles in the horizontal section up to the destination position DL at the height of the current position CL, so a stop such as a power outage during the simultaneous lowering, lateral movement, and traveling movement will not cause a collision due to the horizontal flow. Therefore, when lowering and moving laterally or traveling simultaneously, safe operation can be achieved without collisions by moving along the shortest route or setting a safe height above the winding-down position, which is just a small braking distance away. The safety height is the maximum value of the range between the current position CL and the destination position DL, which is updated sequentially. Because it is calculated from the height, even if there is a low depression between the current position CL and the destination position DL, it will not be lowered too much in the depression, but will instead adjust to the higher position beyond it, allowing for smooth lateral movement toward the destination position DL and simultaneous lowering while traveling.

[0031] We have explained, using examples, a system that prevents collisions between the suspended load HW and obstacles such as coils CO on the floor FL when the hoisting and lowering operations and the three-dimensional traversal and traveling operations are performed by a simple sequence control system.However, in order to derive a more optimal operating path, there is also a method of installing a simulator computer and operating the shortest route. Even in this case, when hoisting and horizontal movement are performed simultaneously, a safety route SR is drawn from the shortest route derived by the simulator, a distance equal to the braking distance BD of the horizontal movement, behind the direction of travel of the horizontal movement, and the load is moved along this route, thereby preventing collision between the load and obstacles such as the coil CO on the floor FL. Furthermore, when lowering and horizontal movement are performed simultaneously, a safety route SR is drawn upward from the shortest route calculated by the simulator by the braking distance BD for lowering, and the load is moved along this route to prevent collisions between the load and obstacles such as the coil CO on the floor FL. Alternatively, the calculation can be performed by taking into account the braking distance being shifted backward in the direction of travel when the simulator is calculating.

[0032] Braking distance refers to the maximum distance at a given speed at which an obstacle does not interfere with the suspended load when braking under various conditions, such as the braking distance with friction braking brakes such as electromagnetic brakes, braking distance with load sway, or braking distance during normal deceleration. At this time, friction braking can fluctuate due to various factors, such as slippage caused by humidity, oil, dust, etc. adhering to the rails, and the influence of the slope and undulation of the rails, and in some cases the braking time caused by friction braking can be longer than the normal deceleration caused by the speed control device.Taking these factors into consideration, it is safe to set the braking distance at a long distance with ample margin.

[0033] Incidentally, we have explained an example in which the coil CO is grasped and transported, but the same applies when moving towards the coil to grasp it; the process is carried out from the first step to the second step to the third step in a manner that avoids interference between the hoisting tool grasping the coil and the coil CO on the floor FL.

[0034] Here, rectangles RA and RA2 are combinations of axes that move horizontally in a straight line, such as the traverse and travel of overhead cranes and bridge cranes, and the travel of terahertz cranes, and each side of rectangle RA and rectangle RA2 is parallel to the traverse and travel. Rotating jib cranes and polar-type rotating overhead cranes have circular partial shapes rather than rectangular shapes, but the concept is the same regardless of the shape. Incidentally, when the traversal distance and the running distance are the same, the result is a square, and the rectangle RA and rectangle RA2 mentioned here include squares. Furthermore, the horizontal movement referred to here refers to the lateral movement or running of overhead cranes, and for rotary cranes, this includes swinging and horizontal retraction.

[0035] Although the example described above concerns the automatic transport of coils, which is a common application example of an automatic crane, the object to be transported is not limited to this; the object to be transported may be a slab, a paper roll, garbage, cement raw material, or any other object, and the invention is not limited to this.

[0036] The crane collision prevention control system of the present invention has been described above based on its embodiments, but the present invention is not limited to the configurations described in the above embodiments, and the configuration can be changed as appropriate within the scope of the invention. [Industrial Applicability]

[0037] The crane collision prevention control system of the present invention avoids the risk of collision between the load and obstacles on the floor that occurs when hoisting and horizontal movements are performed, making it possible to safely perform hoisting and horizontal movements simultaneously.Compared to conventional automatic cranes that hoist the load to a safe height before performing horizontal movements, it is possible to ensure a transport capacity equal to or greater than that of a manually operated crane, and it can be used effectively in industry. [Explanation of symbols]

[0038] CR Automatic Crane HW hanging load CO Obstacles FL floor SL start position FR Shortest Path ER Emergency Route SR Safe Route BD braking distance HV Winding Speed LV travel speed SH Safe Height CL Current position DL target position TL running TS rampant RA rectangle LP driving collision distance SP Traverse collision distance LC Running Collision Line SC Transverse Collision Line LS driving line SS Traverseable Line DP Horizontally movable diagonal position RA2 rectangle

Claims

1. A crane collision prevention control system characterized in that, in a transportation system for an automatic crane that simultaneously performs hoisting and horizontal movement, when hoisting diagonally along the shortest path by hoisting and horizontal movement, the actual movement path is set backward from the shortest path in the direction of horizontal movement by an amount corresponding to the braking distance corresponding to the speed at which the horizontal movement occurs, and the height at which horizontal movement can be freely performed is set to the height at which the highest floor obstacle within a rectangular planar range with the current position and destination position as the diagonal corner when the transportation area of ​​the automatic crane is viewed in a plane.

2. 2. The crane collision prevention control system according to claim 1, wherein, when a space enabling horizontal movement in the direction of the destination is secured while the automatic crane is being hoisted, a travelable line is set that is drawn forward from the collision travel line existing in the travel direction toward the destination position by a braking distance corresponding to the travel speed at that time, and a lateral movement possible line is set that is forward from the collision lateral movement line existing in the lateral movement direction toward the destination position by a braking distance corresponding to the lateral movement speed at that time, and the planar range enclosed by a rectangle having the intersection of the travelable line and the lateral movement possible line and the current position as diagonal corners is made possible for lateral movement or travel operation during hoisting.

3. 3. The crane collision prevention control system according to claim 1, wherein when the height of an obstacle on the floor in a rectangular planar range having diagonal corners of the current position and the target position begins to decrease with horizontal movement, a simultaneous lowering operation is performed during horizontal movement, and the height at that time is moved to a position higher by the braking distance for lowering than the clearance dimension height for avoiding collision.

Images